Stacked Interleaved Transformer Layout for mm-Wave Coupling
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Solution Overview
Problem
At higher frequencies, such as mm-wave frequencies, achieving a high coupling coefficient and low insertion loss in transformer structures becomes challenging due to the smaller size of the transformer, which limits the achievable coupling between coils in both stacked and interleaved designs, especially when manufacturing technology only provides a single thick metal layer.
Innovation Solution
A stacked and interleaved transformer structure is introduced, where a turn of the first coil overlaps a turn of the second coil in both a lateral and vertical direction, combining the advantages of both architectures to increase coupling and reduce insertion loss, and can be integrated into current integrated circuit designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stacked transformer structure is used, then vertical coupling between coils is achieved, but the coupling coefficient is limited at mm-wave frequencies due to smaller transformer size
Solution Approach 1:
The patent combines stacked (vertical) and interleaved (lateral) coupling dimensions to create a hybrid transformer structure. This multi-dimensional approach allows the transformer to achieve high coupling coefficients by utilizing both vertical and lateral magnetic coupling paths, effectively overcoming the size limitations at mm-wave frequencies.
Solution Approach 2:
The transformer structure employs a composite architecture integrating both stacked and interleaved coupling mechanisms. This composite design leverages the advantages of both structures: the vertical coupling of stacked transformers and the lateral coupling of interleaved transformers, resulting in enhanced overall coupling performance.
2Loss of energy
If an interleaved transformer structure is used, then lateral coupling between coils is achieved, but insertion loss remains high at mm-wave frequencies
Solution Approach 1:
By introducing vertical stacking in addition to lateral interleaving, the patent creates a three-dimensional coupling structure. This additional vertical dimension provides alternative magnetic coupling paths that reduce energy loss and improve insertion loss performance at mm-wave frequencies.
Solution Approach 2:
The hybrid stacked-interleaved structure combines two different coupling mechanisms, creating a composite transformer that benefits from both vertical and lateral magnetic coupling. This composite approach reduces insertion loss by providing multiple coupling pathways for magnetic flux.
3Speed
If transformer size is reduced for mm-wave frequencies, then frequency performance is improved, but achievable coupling between coils is limited
Solution Approach 1:
The patent utilizes both lateral and vertical dimensions for coil coupling, creating a three-dimensional transformer structure. This multi-dimensional approach allows high coupling coefficients to be achieved even when the overall transformer footprint is reduced for mm-wave frequency performance.
Solution Approach 2:
The stacked transformer configuration allows coils to be nested in vertical layers, with primary and secondary coils positioned in different metal layers. This nesting approach maximizes coupling within a compact footprint, enabling high-frequency performance while maintaining strong coupling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The stacked/interleaved transformer structure reduces insertion loss, increases the coupling coefficient, and improves the signal-to-noise ratio in radar transceiver systems by enhancing output power and reducing noise figure, while maintaining compatibility with existing designs and manufacturing technologies.
Implementation Method 1
A stacked transformer structure relies on vertical (i.e., transverse) coupling between coils located primarily in different planes. Another type of transformer structure is an interleaved transformer structure. An interleaved transformer structure (also referred to as a planar transformer structure) relies on lateral (i.e., side) coupling between coils located primarily in the same plane.
Data Source
AI summary
A transformer structure may include a first coil having one or more turns, and a second coil having one or more turns. A turn of the one or more turns of the first coil may overlap a turn of the one or more turns of the second coil in a lateral direction substantially along the turn of the first coil and in a vertical direction substantially along the turn of the first coil. In some implementations, the transformer structure may be integrated in a semiconductor device.